Further result on servomechanism design of time-varying nonlinear systems in output-feedback normal form

This paper revisits the servomechanism design problem for uncertain time-varying nonlinear systems which are transformable into an output-feedback normal form. In contrast to some recent results, this class of nonlinear systems takes a more general form. Thus the existing design method is not applicable. After a refined procedure of a time-varying internal model design, the problem is first converted into a stabilization problem for a nonlinear time-varying augmented system. Then an observer-based output feedback control law is shown to achieve the control goal.